Method of and apparatus for tempering wire



(No Model.)

P. PURDY. METHOD 0F ANDAPPARATUS PoR TBMPERING WIRE.

N0. 482,879. Patented Sept. 20, 1892.

771: a7 par UNITED STATES PATENT OFFICE.,

FRED PURDY, OF ENGLEWOOD, ASSIGNOR TO THE AMERICAN SPRING COMPANY, OF CHICAGO, ILLINOIS.

METHoDoF ANDAPPARATUS FOR TEMPERING WIRE.

SPECIFICATION formingrpart of Letters Patent NO. 482,879, dated September 20, 1892. Application filed November '1, 1889. Serial No. 329.533. (No model.)

To all whom it may concern:

Be it known that I, FRED PURDY, a citizen of the United States, residing at Englewood, in the county of Cook" and State of` Illinois, have invented a new and useful Improvement in Methods ofand Apparatus for T empering \Vire,of which the following is aspecitication.

This invention relates to the method of tem periug wirel or ribbons ot'y steel by the use of electricity as the heating agent and is an irnprovement upon the method set forth in the patent to-Frederick Sedgwick, No. 369,560, dated September 6, 1887. A

In the practice of the said Sedgwick invention it has been found that where the wire being treated varied in gage or in the amount of its carbonor in density of material, or where it was unevenlyannealed, the resistance which it would otter to the electrical current would vary proportionately with these causes, so that the beat generated in the wire would be ditferent in degreeiri different sections, some partsbeing heated to a greater degree than others Being thus unevenly heated, when it enters the hardening-bath it assumes different degrees of hardness just in proportion to the dilerent degrees of heat. it has received from the electricity, and the result is that the temper of the wire is hard in some spots and sections, burned in oth`ers, and nsoft in others, formingaspring of uneven temper.

To avoid this ditculty, which I have found to be a serious obstacle to successful electrothermic tempering, I have devised my present invention, which consists in heating the wire at least partially by radiation, instead of relying wholly upon a current passing di-1 rectly through the wire. This heating'by radiation is best accomplished by passing the wire through a tube', which is heated to the requisite degree by connecting it to the poles of a dynamo or other source of electricity,

Y and in which tube the wire is protected from air-draftsand other external disturbing causes which might render the. degree of heat unequal in diterentportions. I have also found that an alternating current in this process is much preferable to the continuous current heretofore used, because it can be more perfectly regulated and be changed .to any required potential to suit variousonditions ings an apparatus designed for the carrying out of my invention and which is the best form of such apparatus now known tome.

In the drawingsL Figure 1 is a side elevation, partly in section, of the apparatus; and Fig. 2 is a section of the tube wherein the wire is heated by`radialion.

In the drawings, A represents a spool loose upon its arbor, upon which the wire c to be tempered is wound, and from which it passes first through aspring-contact B, which is connected by the wires b and d to the dynamo D. It next enters and passes through a tube E, which is designed to protect it from air-d rafts and conserve what heat is imparted to it by the direct current which it may receive from the dynamo between the point B and the other connections with the dynamo presently to be described. This tube I prefer to make of porcelain, and it is fixedly supported by stationary brackets e. I also provide it with a metal plug F at its lower end, such plug having an aperture but slightly larger than `the wire to be treated, the function of which is to guide the wire truly into the center of the heating-tube G and prevent contact by the wire with the interiorsurfaceof the latter tube, and to prevent air-current through the tube. The heating-tube G, the use of which constitutes the main feature of my invention, I make preferably of platinum, as that metal is' highly refractory and nonoxidizable. Itis supported upon electrical connectionsghfrom the converter H, and the latter is connected with the dynamo by the wiresdand 1I. Itis pref-IV erable that the current, which is fed to the wire by theeconnections by the wiredb upon the one side and the connections 'ijonthe other side, shall heat the wire to a degree somewhat less than that required for the tempering. The tube must be raised, of course, to a high temperature, and for this reason it is desirable to coyerfit with a nou-conductor of heat. I employ-for this purpose the packingof asbes- Vtus 'and surround the latter withan outer IOO protecting-tube m. I thus retain all the heat imparted to the inner tube, protect that tube from thc air, and prevent the distortion or bendingT of it' which might accompany the heating tint. to expansion and contraction, while at the same time the wire being treated is eciently covered against all air-drafts which. might affect its temperature. This tube imparts to the wire an even heat at all points, and the same then passes therefrom into the chilling-bath J, which is a tank made, preferably, of wood or similar material and contains the tempering fiuid. It is desirable that the fluid circulate through the inflowpipe L and out through the overflow-pipe M,-

and thus` be kept at a uniform temperature.

N is a cup set into the bath and supplied with shot 'n or other suitable wiping medium, which will serre to remove the bubbles that may form on the wire when it enters the bath. This cup is preferably removable, as thereby the starting of a length of wire through the apparatus is facilitated. The inflow-pipe L may conduct the fluid in the first instance to this cup, and this cup also receives the end of the electric wire j and forms one of the electrodes by which the direct current is sent through the wire. After passing through the cup N the wire being treated is carried around the idler-pulleys O O, and thence ou to the spool, where itis wound. The tube G acts not only to supply any deficiency of heat which there .may be in the wire, but also to equalize the heat throughout its length, so that it passes into the tempering-bath at a uniform temperature. It maybe of any other Acond ucting material which can be heated byelectricity; but I prefer'the platinum tube, as-

speci fied.

lVhile I have shown a current running through the wire from B to N to assist in heating the wire preparatory to the chillingbath, I do not wish to be understood that such feature is requisite, as the tube G can be relied upon as the sole heating device if it be su fiicientl y long and the wire be moved slowly through it. 0f course in any case the passage of the wire should be not too rapid and at a uniform speed.

rlhc operation of the device will be sufficiently understood from wnat has already been said. I have found that the wire takes on a uniform temperature in passing through the heating-tube regardless of variations in the gage or carbon or density or unequal an` sistance-coils S-may be interposed in circuit between the dynamo and wire, and also between the dynamo and converter. The dynamo D should produce an alternating current for reasons already stated. Other currents I find are apt to leave the wire magnetized, and' they are not so easily controlled to the extent requisite.

In order to secure a uniform speed of the Wire in its passage through the apparatus, I pass it around 'a power-driven pulley or roll R, which is located between the chilling-bath and the receiving-spool?, the latter being driven at a speed which will vary with the amount of wire upon it. I do not illustrate the actuating devices of the pulleyRorspool P, as such devices may be greatly varied, and their construction-is well known to all mechanics. v

l. The improvement in the tempering of wire, consisting in heating the wire by means of a current of electricity passing through it and equalizing the vheat by moving the wire through a heated tube and then chilling the wire, substantially as set forth.

2. In apparatus for tempering wire, a dynamo or other source generating an alternating electric current, in combination witl1 a heating-tube G, electric connections from said dynamo to said tube, and other connections adapted to carry the current from the dyname to the wire, substantially as set forth.

FRED PURDY. \Vitnesses:

EDW. S. EvARTs, II. M. MUNDAY. 

